Abstract: Electrocaloric refrigeration technology has emerged as a research hotspot in solid-state cooling due to its advantages of high energy efficiency, miniaturization potential, and environmental friendliness. However, achieving a large adiabatic temperature change (ΔT) and a wide operation temperature (T_span) under low electric fields remains challenging. In this study, (1-x)Pb(Mg_1/3Nb_2/3)O₃-xPbTiO₃ (PMN-PT, x = 0.08, 0.10, 0.12, 0.14) ferroelectric relaxor ceramics with different PT contents were synthesized via a conventional solid-state reaction method. The influence of PT concentration on the electrocaloric performance was investigated. Results indicate that increasing PT content weakens the relaxor characteristics, reduces dielectric frequency dispersion, and drives relaxor ferroelectric behavior toward normal ferroelectric. Notably, the 0.88PMN-0.12PT ceramic exhibits outstanding electrocaloric properties under a low electric field of 50 kV/cm, achieving a maximum ΔT of 1.60 K, with ΔT exceeding 0.5 K across a broad temperature range of 30-180 ℃. Piezoresponse force microscopy (PFM) exhibits uniformly distributed long-range ferroelectric domain structure in the sample. The electrocaloric effect originates from entropy changes induced by the transition of ferroelectric domains from an ordered to a disordered state during electric field unloading. By integrating dielectric, ferroelectric, and domain structure analyses, the correlation between the diffuse phase transition of relaxor ferroelectrics and their wide-temperature-range electrocaloric performance is elucidated. This study provides theoretical guidance for designing lead-based electrocaloric materials compatible with low-field driving and wide temperature ranges, demonstrating their potential for applications in solid-state refrigeration devices.

Key words: lead magnesium niobate-lead titanate, electrocaloric effect, relaxor ferroelectrics, wide operating temperature